Modular design of locally ordered tetrahedral structures of Si,SiO2, and H2O: I. investigation of the possible cooperative local crystallization in amorphous matrices of these compounds

The hypothesis is put forward that the structure of amorphous silicon and other amorphous compounds with a tetrahedral coordination of atoms consists of local regions characterized by an ordered but not crystalline structure and that, owing to the regularity inherent in this structure, solid-phase crystallization of the amorphous compounds under consideration can occur through the cooperative mechanism. The modular design is used to construct a possible structure of similar local regions and to describe the mechanism of its cooperative transformation into a diamond-like structure with the possible formation of numerous microtwins. The difficulties encountered in the course of the cooperative transformation are considered. Algorithms are proposed for constructing one more connected structure of local regions from the same modules (closed hollow loops of bonds), which undergoes a cooperative transformation into crystalline silicon without the aforementioned difficulties.